JOSHUA MESERVEY is Assistant Director of the Atlantic Council’s Africa Center. Follow him on Twitter @jmeservey.

Sadly, the al Shabab attack[1] on Kenya’s Garissa University College that killed at least 147 people was nothing new. Since October 2011, when Kenya invaded Somalia to fight the terrorist group in its home territory, the group has launched more than 100 attacks[2] inside Kenya that have claimed hundreds of lives and sent the country’s tourism industry into a tailspin. Many of the attacks have been as ruthless as this latest outrage: the group killed at least 67 in an attack on the Westgate Mall in Nairobi in September 2013, and in June 2014 took over a Kenyan town and systematically executed[3] its non-Muslim residents.

Goran Tomasevic / Reuters

A pastor prays during an Easter Sunday service in a church in Garissa, April 5, 2015.

Even so, al Shabab has been wounded by a sustained offensive from the multinational African Union Mission in Somalia (AMISOM), and its deeds are increasingly eclipsed by the lurid exploits of the Islamic State of Iraq and al-Sham (ISIS) and Boko Haram. As the group feels its stature weaken, it is more likely to lash out, carrying out high-profile and gratuitously brutal attacks like the one in Garissa. The United States and the rest of the international community must do all they can to support Kenya as it weathers al Shabab’s grisly turn.

Al Shabab was once one of the premier terror groups in the world. Years before ISIS gobbled up sections of Syria and Iraq, al Shabab conquered and then governed most of southern Somalia. Its mix of religious and nationalist appeals drew in recruits from around the globe, including dozens of Somali Americans[4].

But the group has been in decline since its apex in 2010. AMISOM has driven it from all its major strongholds, and its fighters have defected in droves. It once raised millions of dollars a year in taxes on goods coming into the ports it controlled and from the people under its dominion, but as its territory has shrunk, its revenue almost certainly has as well.